As indicated above, the dynamic splint of the present invention is applicable to various hinged joints such as the finger, elbow, wrist, shoulder, hip, knee, ankle and toe joints. It will, for purposes of illustration, be described in its application to an elbow joint, although its use is not intended to be so limited.
In the case of an arm or elbow fracture or break, the arm is set and provided with a cast. Normally the cast immobilizes the arm in a bent condition generally at about 45 degrees. When the cast is ultimately removed, it is usually found that the flexion muscle group over time has been partially absorbed and thus has been shortened. At the same time, the opposition muscle group (i.e. the extension muscle group) has been stretched, causing it to grow longer. The flexion muscle group, when stretched by the extension muscle group (which is contracting), is not long enough to allow full extension of the arm. The term "contracture" is often used to define this condition. Similarly, since the extension muscle group has elongated, it cannot contract enough to fully extend the arm. As a result of this, the patient loses part of the normal active range of movement, say from about 40 degrees or 20 degrees to +15 degrees, as will be further explained hereinafter.
In recent years, attention has been turned to dynamic splints. This is based upon the belief that a constant dynamic low intensity stress to remodel contracted and scarred connective tissue may be more efficient and safer than traditional range-of-motion exercises and passive stretching by a therapist. A constant state of tension appears to trigger and optimize the remodeling process, a process which may be home-based rather than clinic-based.
Laboratory studies show that the best way to permanently lengthen contracted connective tissue, without compromising its structural integrity, is by prolonged low intensity stressing (stretching). Tests further show that contracted connective tissue, when continuously stretched at a constant low intensity force (in the form of torque), remodels more rapidly, requiring less rehab time and less cost.
While showing promise, present day dynamic splints have several major drawbacks. Most dynamic splints cannot maintain a constant force (torque) without frequent adjustment. The adjustments must be correctly made or the benefits of the splint are geatly diminished. If improperly made, the adjustments may result in ineffective torque levels, that may damage fragile tissue, cause pain, prolong rehabilitation, and may interfere with or inhibit the normal function of the extremity.
As indicated above, patients with a range-of-motion loss have a range of loss which is simply a part of the overall normal range of movement of the limb (in this instance an arm). Thus, the patient has, with respect to the normal over-all range of motion, an active range through which he can move his arm and a passive range through which he cannot move his arm. Clinical efforts would be targeted at the passive range, only, but prior art dynamic splints have not been capable of doing this. Prior art dynamic splints provide torque over a predetermined range of motion, dictated by the nature of the mechanism of the splint. Prior art splints do not discriminate between the active and passive ranges within the over-all range of motion. As a result of this, the splint may provide a passive assist to active muscle activity which may impair the normal muscle activity which the patient already has, and which may interfere with or inhibit the absorption of adaptively lengthened muscle and thus prolong and complicate the recovery process. The splint may also trigger unwanted neurological response which may inhibit extremity use and use of the splint, further complicating recovery.
It is an object of the present invention to provide a dynamic splint which creates within the passive zone a torque to influence the synthesis of new tissue with respect to the contracted muscle group. It keeps the contracted tissue in a constant state of mild tension within the passive range of motion, so that cells multiply and proliferate in response to the need created by the mild stress applied by the splint. The range of torque can be adjusted depending upon the application of the splint.
It is an object of the present invention to provide a dynamic splint which will not supply a passive assist to the stretched extension muscle group, retarding its partial absorption or shortening and thereby impeding the achievement of a normal range of movement.
It is an object of the present invention to provide a dynamic splint which will apply torque only in the targeted treatment range (i.e. the passive range) of the overall normal range of movement.
It is an object of the present invention to provide a dynamic splint which will supply a constant therapeutic torque only to the contracted muscle group, and only within its passive range.
It is an object of the present invention to provide a dynamic splint the constant therapeutic torque of which can be easily and accurately adjusted.
It is an object of the present invention to provide a dynamic splint, wherein the adjustable constant torque is supplied by a spring and a dedicated cam, together with a pair of gears.
It is an object of the present invention to provide a dynamic splint which, when used in association with an orthopedic or neurological malady, can have the amount of torque it applies and the passive range over which it applies the torque easily adjusted to minimize or eliminate problems of spasticity and/or tissue trauma.
It is an object of the present invention to provide the dynamic splint with a pivotable distal cuff member.
It is an object of the invention to provide a dynamic splint which, when located within the active zone, can be easily adjusted and easily applied and removed without having to lock the splint.
It is an object of the present invention to provide a dynamic splint which can be used in lieu of range-of-motion exercises and actual stretching techniques.
It is an object of the present invention to provide a dynamic splint which can be used in orthopedic areas and non-orthopedic areas such as stroke, multiple sclerosis, cerebral palsy, burns and the like.
It is an object of the present invention to provide a dynamic splint which can be locked to form a rigid immobilizing splint.
It is an object of the present invention to provide a dynamic splint with means to lock the spring and eliminate the application of torque.
It is an object of the present invention to provide a dynamic splint which is nice looking, compact, lightweight, of simple construction, inexpensive to manufacture, easily applied, easily adjusted, easily removed and comfortable.
It is an object of the present invention to provide a dynamic splint of such nature that a patient will willingly comply to the requirements of its use.